| Autor: |
Alabugin IV; Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390, United States., Eckhardt P; Department of Chemistry, Johannes Gutenberg University, Duesbergweg 10-14, 55128 Mainz, Germany., Christopher KM; Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390, United States., Opatz T; Department of Chemistry, Johannes Gutenberg University, Duesbergweg 10-14, 55128 Mainz, Germany. |
| Jazyk: |
angličtina |
| Zdroj: |
Journal of the American Chemical Society [J Am Chem Soc] 2024 Oct 09; Vol. 146 (40), pp. 27233-27254. Date of Electronic Publication: 2024 Sep 24. |
| DOI: |
10.1021/jacs.4c10422 |
| Abstrakt: |
Although photoredox catalysis is complex from a mechanistic point of view, it is also often surprisingly efficient. In fact, the quantum efficiency of a puzzlingly large portion of photoredox reactions exceeds 100% (i.e., the measured quantum yields (QYs) are >1). Hence, these photoredox reactions can be more than perfect with respect to photon utilization. In several documented cases, a single absorbed photon can lead to the formation of >100 molecules of the product, behavior known to originate from chain processes. In this Perspective, we explore the underlying reasons for this efficiency, identify the nature of common catalytic chains, and highlight the differences between HAT and SET chains. Our goal is to show why chains are especially important in photoredox catalysis and where the thermodynamic driving force that sustains the SET catalytic cycles comes from. We demonstrate how the interplay of polar and radical processes can activate hidden catalytic pathways mediated by electron and hole transfer (i.e., electron and hole catalysis). Furthermore, we illustrate how the phenomenon of redox upconversion serves as a thermodynamic precondition for electron and hole catalysis. After discussing representative mechanistic puzzles, we analyze the most common bond forming steps, where redox upconversion frequently occurs (and issometimes unavoidable). In particular, we highlight the importance of 2-center-3-electron bonds as a recurring motif that allows a rational chemical approach to the design of redox upconversion processes. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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